# X-linked lymphoproliferative disease type 1 (SAP deficiency)

Source: https://onco.cc/terms/x-linked-lymphoproliferative-disease/  
OnCo record `x-linked-lymphoproliferative-disease` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

X-linked lymphoproliferative disease is a rare inherited immune deficiency, mainly in boys, caused by a fault in the SH2D1A gene, in which the glandular fever virus can trigger a life-threatening overreaction of the immune system or lymphoma. A stem cell transplant is the treatment that changes its course.

## Summary

X-linked; SH2D1A encodes SAP, the SLAM-associated protein, identified in 1998. Epstein-Barr virus infection drives haemophagocytic lymphohistiocytosis, hypogammaglobulinaemia and lymphomas; most present before age 10, though adult onset and affected females are reported (Frontiers in Immunology 2025 review).

B-cell lymphomas are treated with standard chemotherapy followed by expedited haematopoietic stem cell transplantation; haemophagocytic lymphohistiocytosis with the HLH-1994 regimen, with ruxolitinib reported as salvage or bridge; immunoglobulin replacement for hypogammaglobulinaemia. In a Japanese cohort of 33 patients, 21 of those not transplanted died of the disease and its complications, while 11 of 12 transplanted survived; early transplantation for asymptomatic patients is suggested and gene therapies are in development.

## Fields

- Kind: Term
- Last checked: 2026-11-04
- Also known as: XLP; XLP1; XLP-1; Duncan disease; Purtilo syndrome; SAP deficiency; SH2D1A deficiency
- Tags: gap-fill; hereditary

## Notes

- Orphanet ORPHA:538931. SH2D1A has no target record in OnCo.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/X-linked_lymphoproliferative_disease
- Li, Front Immunol 2025: X-linked lymphoproliferative disease type 1, a clinical and genetic update: https://doi.org/10.3389/fimmu.2025.1620327
- Orphanet ORPHA:538931: https://www.orpha.net/en/disease/detail/538931

## Connected records

- technologies: [Allogeneic stem cell transplantation](https://onco.cc/technologies/allogeneic-hsct/), [Germline (hereditary) testing](https://onco.cc/technologies/germline-testing/)
- terms: [Hereditary cancer syndromes](https://onco.cc/terms/hereditary-cancer-syndromes/)

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